A FLUOROMETRIC FIBEROPTIC BIOSENSOR FOR DUAL ANALYSIS OF GLUCOSE AND FRUCTOSE USING GLUCOSE-FRUCTOSE-OXIDOREDUCTASE ISOLATED FROM ZYMOMONAS-MOBILIS

A fluorometric fiber-optic biosensor was used to determine the content of glucose and fructose according to the measurement principle of flo w injection analysis (FIA). The enzyme glucose-fructose-oxidoreductase (GFOR) isolated from Zymomonas mobilis was confined in a measurement cell behind an ultrafiltration membrane. The GFOR catalyzes the oxidat ion of glucose to gluconolactone and the reduction of fructose to sorb itol according to the ping-pong mechanism. This unique enzyme contains NADPH tightly confined in the enzyme complex. The change of NADPH flu orescence was detected by a fluorosensor. The stability could be incre ased remarkably by crosslinking with glutaraldehyde. The detection ran ge for glucose was within a concentration range of 0.055-55.5 mM and t hat for fructose within 0.278-331 mM. The response time for glucose an d fructose was in the range of 40 s and 1 min, respectively. Steady-st ate was achieved for glucose injection in 2 min and fructose injection in 6.5 min. Sampling time for glucose could be reduced to 37% by incl uding fructose in excess to the sample. This also makes the regenerati ng step unnecessary. The specificity of this biosensor was tested for different sugars. The results showed that this biosensor system is hig hly specific, sensitive and suitable for dual analysis of glucose and fructose.